内容概要&＃xff1a;
1. LB、LVS介绍
LB集群是load balance 集群的简写&＃xff0c;翻译成中文就是负载均衡集群
LVS是一个实现负载均衡集群的开源软件项目
LVS架构从逻辑上可分为调度层(Director)、server集群层(Real server)和共享存储层
LVS可分为三种工作模式: NAT(调度器将请求的目标ip即vip地址改为Real server的ip, 返回的数据包也经过调度器&＃xff0c;调度器再把源地址修改为vip), TUN(调度器将请求来的数据包封装加密通过ip隧道转发到后端的real server上&＃xff0c;而real server会直接把数据返回给客户端&＃xff0c;而不再经过调度器), DR(调度器将请求来的数据包的目标mac地址改为real server的mac地址&＃xff0c;返回的时候也不经过调度器&＃xff0c;直接返回给客户端)
三种IP&＃xff1a;DIP(driector ip), VIP(virtual ip), RIP(Real IP). 其中DIP, RIP 为同一个网段&＃xff0c;并且为私网IP, vip为对外提供服务的ip&＃xff0c;Director, Real server上都设置vip
LVS的调度算法&＃xff1a;轮叫调度(Round Robin)(简称rr) ,加权轮叫(Weighted Round Robin)(简称wrr),最少链接(least connection)(LC),加权最少链接(Weighted Least Connections)(WLC) 等等
2. LVS/NAT 配置
三台服务器一台作为director, 两台作为real server
Director 有一个外网ip (192.168.0.11) 和一个内网ip(192.168.200.11), 两个real server上只有内网ip(192.168.200.128)和(192.168.200.129) 并且需要把两个real server的内网网关设置为director的内网ip(192.168.200.11)
两个real server 上都安装httpd: yum install -y httpd
Director上安装ipvsadm yum install -y ipvsadm
Direcotr 上 vim /usr/local/sbin/lvs_nat.sh //增加:
#! /bin/bash
# director 服务器上开启路由转发功能:
echo 1 > /proc/sys/net/ipv4/ip_forward
echo 0 > /proc/sys/net/ipv4/conf/all/send_redirects
echo 0 > /proc/sys/net/ipv4/conf/default/send_redirects
echo 0 > /proc/sys/net/ipv4/conf/eth0/send_redirects
echo 0 > /proc/sys/net/ipv4/conf/eth1/send_redirects
# director 设置nat防火墙
iptables -t nat -F
iptables -t nat -X
iptables -t nat -A POSTROUTING -s 192.168.200.0/24 -j MASQUERADE
# director设置ipvsadm
IPVSADM&＃61;&＃39;/sbin/ipvsadm&＃39;
$IPVSADM -C
$IPVSADM -A -t 192.168.0.11:80 -s lc -p 300
$IPVSADM -a -t 192.168.0.11:80 -r 192.168.200.128:80 -m -w 1
$IPVSADM -a -t 192.168.0.11:80 -r 192.168.200.129:80 -m -w 1
直接运行这个脚本就可以完成lvs/nat的配置了:
/bin/bash /usr/local/sbin/lvs_nat.sh
通过浏览器测试两台机器上的httpd内容
3. LVS/DR 配置
三台机器:
director(eth0192.168.0.11, vip eth0:0: 192.168.0.100)
real server1(eth0 rip: 192.168. 0.21, vip lo:0: 192.168.0.100)
real server2(eth0 rip: 192.168.0.22, vip lo:0: 192.168.0.100)
Director 上 vim /usr/local/sbin/lvs_dr.sh //增加
#! /bin/bash
echo 1 > /proc/sys/net/ipv4/ip_forward
ipv&＃61;/sbin/ipvsadm
vip&＃61;192.168.0.100
rs1&＃61;192.168.0.21
rs2&＃61;192.168.0.22
ifconfig eth0:0 $vip broadcast $vip netmask 255.255.255.255 up
route add -host $vip dev eth0:0
$ipv -C
$ipv -A -t $vip:80 -s rr
$ipv -a -t $vip:80 -r $rs1:80 -g -w 1
$ipv -a -t $vip:80 -r $rs2:80 -g -w 1
两台rs上&＃xff1a;vim /usr/local/sbin/lvs_dr_rs.sh
#! /bin/bash
vip&＃61;192.168.0.100
ifconfig lo:0 $vip broadcast $vip netmask 255.255.255.255 up
route add -host $vip lo:0
echo "1" >/proc/sys/net/ipv4/conf/lo/arp_ignore
echo "2" >/proc/sys/net/ipv4/conf/lo/arp_announce
echo "1" >/proc/sys/net/ipv4/conf/all/arp_ignore
echo "2" >/proc/sys/net/ipv4/conf/all/arp_announce
sysctl -p
然后director上执行: bash /usr/local/sbin/lvs_dr.sh
两台rs上执行: bash /usr/local/sbin/lvs_dr_rs.sh
Windows下浏览器测试访问
4. LVS/DR &＃43; keepalived配置
前面的lvs虽然已经配置成功也实现了负载均衡&＃xff0c;但是我们测试的时候发现&＃xff0c;当某台real server把httpd进程停掉&＃xff0c;那么director照样会把请求转发过去&＃xff0c;这样就造成了某些请求不正常。所以需要有一种机制用来检测real server的状态&＃xff0c;这就是keepalived。它的作用除了可以检测rs状态外&＃xff0c;还可以检测备用director的状态&＃xff0c;也就是说keepalived可以实现ha集群的功能&＃xff0c;当然了也需要一台备用director.
备用director也需要配置主director上的那个lvs_dr.sh脚本&＃xff0c;两个direcotr上需要安装一下keepalived软件
yum install -y keepalived
安装好后&＃xff0c;编辑配置文件
vim /etc/keepalived/keepalived.conf //加入如下&＃xff1a;
vrrp_instance VI_1 {
state MASTER #备用服务器上为 BACKUP
interface eth0
virtual_router_id 51
priority 100 #备用服务器上为90
advert_int 1
authentication {
auth_type PASS
auth_pass 1111
}
virtual_ipaddress {
192.168.0.100
}
}
virtual_server 192.168.0.100 80 {
delay_loop 6 #(每隔10秒查询realserver状态)
lb_algo wlc #(lvs 算法)
lb_kind DR #(Direct Route)
persistence_timeout 60 #(同一IP的连接60秒内被分配到同一台realserver)
protocol TCP #(用TCP协议检查realserver状态)
real_server 192.168.0.21 80 {
weight 100 #(权重)
TCP_CHECK {
connect_timeout 10 #(10秒无响应超时)
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
real_server 192.168.0.22 80 {
weight 100
TCP_CHECK {
connect_timeout 10
nb_get_retry 3
delay_before_retry 3
connect_port 80
}
}
}
以上为主director的配置文件&＃xff0c;从director的配置文件只需要修改
state MASTER -> state BACKUP
priority 100 -> priority 90
另外&＃xff0c;需要注意的是&＃xff0c;一定要先执行脚本&＃xff0c;再启动keepalived服务&＃xff0c;启动命令/etc/init.d/keepalived start
5. 使用nginx实现lb集群
Nginx调度器(外网ip:192.68.0.11, 内网ip: 192.168.200.11)
Web1(内网ip: 192.168.200.128)
Web2(内网ip: 192.168.200.129)
Centos 6下如果安装过epel的yum源可以直接yum安装nginx yum install -y nginx
或者源码包编译nginx, 官网地址http://nginx.org/ 下载合适版本&＃xff08;最好不要最新&＃xff09;
下载后解压编译安装:
./configure --prefix&＃61;/usr/local/nginx; make; make install
源码包cd /usr/local/nginx/conf; yum安装 cd /etc/nginx
vim nginx.conf // 增加
include lb.conf;
vim lb.conf //增加如下
upstream abc.com {
server 192.168.200.128;
server 192.168.200.129;
}
server {
listen 80;
server_name www.abc.com;
location / {
proxy_pass http://abc.com/;
proxy_set_header Host $host;
proxy_set_header X-Real-IP $remote_addr;
proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
}
}
启动nginx&＃xff1a; service nginx start
测试&＃xff1a;curl -x192.168.0.11:80 www.abc.com/1.html
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